1. Field of the Invention
The present invention generally relates to magnetic disk units, and more particularly to a magnetic disk unit which is provided with a head having a magneto-resistive (MR) element.
Recently, in magnetic disk units, a MR element is used as a reproducing head because of the high output obtainable thereby. A resistance of the MR element changes depending on the magnetic information recorded on a magnetic disk. The information recorded on the magnetic disk is reproduced by detecting the change in the resistance of the MR element by supplying a sense current to the MR element.
2. Description of the Related Art
In a conventional magnetic disk which uses the MR element, the sense current is set so that a predetermined characteristic and a desired serviceable life are obtained under a high temperature environment, from the point of view of the serviceable life of the MR element. Normally, the sense current which is set in this manner is fixed when forwarding the magnetic disk unit.
In other words, in the conventional magnetic disk unit, the sense current is suppressed and set to satisfy a guaranteed serviceable life of the magnetic disk unit even under the high temperature environment, so that the MR element satisfies the guaranteed serviceable life of the magnetic disk unit.
In the conventional magnetic disk unit, it is thus possible, at room temperature or under a low temperature environment, to supply a sense current which is larger than the sense current which is set as described above. However, the sense current is suppressed and set to satisfy the guaranteed serviceable life of the magnetic disk unit under the high temperature environment, and there was a problem in that the original performance of the MR element is not fully utilized.
Accordingly, it is a general object of the present invention to provide a novel and useful magnetic disk unit in which the problem described above is eliminated.
Another and more specific object of the present invention is to provide a magnetic disk unit which controls a sense current supplied to a MR element, so that a desired serviceable life of the magnetic disk unit is obtained and the original performance of the MR element is fully utilized.
Still another object of the present invention is to provide a magnetic disk unit comprising a housing which accommodates a magneto-resistive element and a magnetic disk, temperature detecting means for detecting a temperature within the housing, resistance detecting means for detecting a resistance value of the magneto-resistive element, and current control means for controlling a sense current which is supplied to the magneto-resistive element, based on the temperature detected by the temperature detecting means and the resistance value detected by the resistance detecting means. According to the magnetic disk unit of the present invention, it is possible to control the sense current which is supplied to the magneto-resistive element so that a desired guaranteed serviceable life of the magnetic disk unit is obtained and the original performance of the magneto-resistive element can be fully utilized.